The invention relates to an X-ray diagnostics installation comprising an electronic transmission channel with a television pickup tube, said electronic transmission channel transmitting the x-radiation issuing from the patient.
It is prior art to electronically intensify the x-ray image by means of an x-ray image intensifier, to pick up the output image of the x-ray image intensifier with the aid of a television pickup tube, and to reproduce this image, for example, via a television display unit. In this case, it is possible to also photograph the image on the television display unit by means of a camera. If a normal vidicon is used as the television pickup tube for an x-ray diagnostics installation of the type initially cited, the comparatively great inertia (response lag) has an adverse effect. A vidicon-type camera tube having a lead oxide photoconductive layer provides a higher speed of response to changing light patterns, but is virtually ruled out on account of too great a transverse conductivity of the target. When using a television pickup tube having a cadmium-selenide (CdSe) layer; for example, an image pickup tube sold under the trademark "Chalnicon", the transverse conductivity of the layer is indeed sufficiently low; however, this tube does not attain the low inertia of a lead oxide type of vidicon, and like the tubes having a lead oxide layer, it has the undesirable property that the free surface of the layer becomes charged to negative potentials during scanning of the target in the absence of an input light signal. The consequence of this is a signal compression in the dark image regions.